Rotavirus is the most common cause of severe acute infectious diarrheal disease among infants and children, and as such its implication as the diarrheal agent in a patient would allow discontinuance of unnecessary and costly empiric antibacterial therapy. Four commercially available monoclonal antibody - based enzyme immunoassay (EIA) kits: 1) Rotaclone (Cambridge Bioscience, Worcester, MA), 2) TestPak Rotavirus (Abbott Labs, N. Chicago, IL), 3) Rota-CUBE (Difco Labs, Detroit, Michigan), and 4) Pathfinder Rotavirus (Kallestad Diagnostics, Austin, TX), are currently being evaluated for their ability to detect rotavirus antigen in stool specimens submitted from children and adults with acute diarrhea. A statistical study will be performed comparing the sensitivities, specificities, and positive and negative predictive values of these test kits.